Yeah it’s pretty much the same as virus scanners not catching everything – you also need a malware scanner. Between the pair of tools I don’t see a lot of unwanted content pop up in my browser, and there are a few paywalls on smaller sites that seem to get knocked down. I did run into one problem though, trying to pay my gas bill and the page required access to a site that was marked with high warnings in both add-ons. I think they finally changed it, but you would think anyone collecting money online would do better research into the tools they used.